Power Conditioning / Surge Protection

You want to protect and to filter.  The problem is that filtering places resistance in series that causes big voltage drops and kills dynamics.  Most of power supplies take current from mains in short spike of huge amplitude (about 10 fold of average).  I use Furman Elite 20PFi.  They call it "Power Factor Correction", but in reality it is huge inductor in series with large capacitor (in parallel to load) that stores energy delivering up to 55A current for spikes (it presents resistive load to mains).  It also has very tight non-sacrificial over/under voltage protection with circuit breaker, that resets itself.

https://www.furmanpower.com/product/conditioner-power-ht-20a-power-factor-ELITE-20%20PF%20I

In addition, I installed whole house protection in form of dual 20A breaker (Siemens panel style), by just swapping breakers.  Even if you have to hire electrician it is worth it.  Today everything is electronic, including appliances and even bulbs.

"Balanced surge protection" is an interesting name.   Since our USA 120VAC power is split phase, single ended, balanced means it either works for 240VAC, which is balanced, or it applies the same filtering on the line and the neutral, even though it is an unbalanced line.   (The only other option is it just a cool name and has nothing to do with the design.)

There are two schools of thought among engineers here.   Some believe filters on the neutral line is a good idea, others don't.   If you design this stuff, you will be in one group or the other, to be sure.   

All the surge devices for which I design at work, have filters on the line and neutral.    For audio work, I leave the earth connection alone, for industrial stuff, it often has voltage limiting on it from neutral to earth. 

The "inductor in parallel with the line" term must mean in series with the line, since it is counter productive to put it in across the line, and in parallel means the line is shorting it out.   If they mean something else, then it is not in parallel with the line.

Stick with the Gray’s. They are parallel circuit devices....I have a 30 amp and 20 amp dedicated line installed. I live in S. Fl and I have a custom 1200 for the majority of my equipment(t.t., phono drive, Rowland model 12, Marantz BluRay, Classe processor, 2 other Jeff Rowland amps for surround) since 2009 and I also have 2 400’s daisy chained with my Jeff Rowland amp and Focal sub on the other side plugged into it....A custom 1200 is basically 2 400’s....
I have been in correspondence with Alex, the president of Richard Gray, as I had the same questions as you do about whether or not to pull the Gray’s out or not. Also in correspondence with the president of Straight Wire who lives in proximity to me(as I have S.W. power mains) and he has a custom 1200 to protect his gear. The Gray’s are well designed. And if I could ever have a confirmatory opinion, it was from Jeff Rowland himself. I asked him about the Grays. Will they detract from the sound. His Response:

Jeff Rowland (Jeff Rowland Design Group)

Aug 27, 2020, 8:58 AM MDT

"Just leave the Grays on for the added ac mains protection. They most likely will not affect the performance in any way and likely improve the overall performance.

The advice to not use added power conditioners is a general statement because there are some types that can limit current or regenerator types that do not work well with the power factor correction circuitry in some of our products. You should be fine with the Grays."

If Jeff tells me the Gray’s are good, I am good...And while I have never had a lightning strike on my house, from what I’ve read, a Gray has never failed or melted down from a strike.

So now, I’m in discussion with Jerry from Straight Wire to replace the Gray’s stock power mains and replace them with their 9 gauge Pro Thunder mains.

But, Richard Gray does sell a house surge protector to be installed at the circuit breaker. I may ask Alex about that.
By the by, my system sound fantastic. I'm not losing any sonics with the Gray's.

I hope this helps.

I go with cool meaningless name for "balanced surge protection". Whole house is the way to go. Better to have the surge protection as far from the equipment as possible.

Does it really kill dynamics? Unless you are clipping what is the mechanism by why "dynamics" are reduced? How would it be different from the normal line voltage variation from say 120-127?

Wouldn't that resistance make the spikes smaller and reduce noise and distortion?

The problem is that filtering places resistance in series that causes big voltage drops and kills dynamics.

audio2design, Let's assume that amp draws from mains 1A during music peaks.  It will likely be drawn in spikes of amplitude reaching 10A.  If filtering coil has 1 ohm resistance it will cause voltage drop of 10V equivalent to 20% of max power loss.  In addition inductor in series supposed to filter out high frequency content (electrical noise) while normal current (narrow spikes) also has high frequency energy.  Of these two factors I would guess that inductive reactance of the coil will have bigger effect, unless inductor has high resistance (thin wire).  Such power loss might only limit maximum output peaks in well regulated amplifiers but might still be audible at any output power in less regulated amps (zero feedback etc.)

My amp has the same dynamics plugged into Furman or the wall.  Many people reported loss of dynamics with conditioners and that's the only plausible explanation I can come up with.